This invention generally relates to reclosable plastic bags, and a method of their manufacture that is more efficient and economical than conventional methods and devices.
An illustrative patent is U.S. Pat. No. 5,461,845 to Yeager (xe2x80x9cYeager ""845 patentxe2x80x9d). There are at least two definitive shortcomings with the technology described therein. The first shortcoming relates to the problem of having to open the zipper completely from the front panel of the finished bag. Users of reclosable bags and packaging are accustomed to opening the profiled fastener from the xe2x80x9ctopxe2x80x9d of the package, and not from the front panel of the package. Hence, the user will have to become accustomed to an unfamiliar or uncomfortable manner in which to open a bag.
The second shortcoming is more serious, and relates to the requirement of opening the package from the front panel thereof. If the package is to be opened from the front panel, a cut or perforation must be made before the fastener is applied. This cut, or perforation, is generally shaped like an xe2x80x9covalxe2x80x9d with opening xe2x80x9ctabsxe2x80x9d for gaining access to the fastener. Since the fastener, most likely, is not closed at the ends of the fastener, the possibility of contamination exists.
The most expedient and economical way to make the package is to create the cut, or perforation, in one operation, just upstream of the fastener strip application. This operation, in its simplest form, will leave openings for potential contamination to pass through the cut or perforated front panel opening. To overcome this contamination potential, users of this method add a great deal more cost and complexity to create a sealed, sealable xe2x80x9cpatchxe2x80x9d, or some other means of eliminating this contamination risk. The same problem occurs, if the package must be hermetically sealed.
Another example of the prior art includes U.S. Pat. No. 4,909,017 to McMahon (xe2x80x9cMcMahon ""017 patentxe2x80x9d). A particular problem with the McMahon ""017 technique is that one obtains a naturally curled thin strip fastener that ultimately makes the fastener unstable, and irregularly shaped. In addition to the problem of sealing the backside of this unstable, irregular-shaped strip fastener to the bag wall(s), there is the problem of keeping the material from naturally curling after sealing the strip to a bag wall, making it even more difficult to get a uniform seal on the backside of the fastener strip.
Hence, there exists a need to solve the problems in the art that are articulated above.
Accordingly, it is an object of the invention to overcome the shortcomings of the prior art by providing a reclosable back-seam bag that provides a hermetic seal by sealing a bag body with a top seal, a bottom seal, a back seam seal, and a plurality of seals sealing a reclosable fastener with flanges to a front wall and a back wall of the bag body.
It is a further object of the invention to provide a reclosable bag having a reclosable fastener assembly that includes two ends, a first continuous elongated profile strip and a second continuous elongated profile strip. The first continuous elongated profile and the second continuous elongated profile provides an airtight and/or watertight seal upon interconnection thereof.
It is yet a further object of the invention to provide an airtight and/or watertight side seal at each end of the reclosable fastener assembly. Each of the side seals connects an end of the reclosable fastener assembly to an inside surface of the front wall and an inside surface of the back wall of the bag.
It is another object of the invention to provide a continuous airtight and watertight lower seal along the length of the reclosable fastener assembly positioned below the profiles. The lower seal connects the reclosable fastener assembly to the front wall. Yet another continuous airtight and watertight upper seal is provided along the length of the reclosable fastener assembly and positioned above the profiles. The upper seal connects the reclosable fastener assembly to the back wall of the bag body.
Another object of the invention is to provide a bag with a first continuous elongated profile strip that has a front wall connecting flange and a gripping flange. Both the front wall connecting flange and the gripping flange have a width greater than a width of the first continuous elongated profile strip to assist in positioning and sealing of the reclosable fastener to web stock. The front wall-connecting flange is sealed to the front wall of the bag.
The invention further provides a bag with a second continuous elongated profile strip that has a back wall-connecting flange. The back wall connecting flange has a width greater than a width of the second continuous elongated profile strip so that the back wall connecting flange can be easily sealed to the back wall. The length of the reclosable fastener assembly is less than the width of the back wall of the bag to provide ease of sealing of the side seals of the bag.
It is a further object of the invention to provide a frangible access that is substantially parallel to the reclosable fastener assembly. Upon opening, the frangible access exposes the reclosable fastener assembly. The frangible access is located on the front wall and on the back wall of the bag body adjacent the reclosable fastener assembly and above the upper seal.
It is yet another object of the invention to provide a reclosable back-seam bag in which the first continuous elongated profile strip and the second continuous elongated profile strip each have respective back portions. The back portions can move in relation to the inside surface of the rectangular sheet and thus provide the bag with greater flexibility and tear resistance.
It is a further object of the invention to provide a reclosable back-seam bag having a gripping flange that includes a continuous rib located at a distal end of the gripping flange and/or a plurality of continuous, substantially parallel ribs located on the gripping flange. The ribs and the gripping flange provide a user with ease of opening of the reclosable fastener once the frangible access has been opened.
Yet another object of the invention is to provide a method of making a reclosable back-seam bag. The method includes the steps of providing a rectangular sheet of polymeric material having an inside surface. A predetermined length of a reclosable fastener including two ends, and a first continuous elongated profile strip interlocked with a second continuous elongated profile strip is provided, and a front wall connecting flange of the reclosable fastener is connected to the inside surface of the rectangular sheet.
The method includes the step of forming a bag body having a front wall and a back wall. The back wall is formed by folding the rectangular sheet of film along two longitudinal folds, and overlapping and sealing edges of the rectangular sheet.
The method further includes joining the front wall to the back wall at a bottom seal, and connecting a back wall connecting flange to the inside surface of the rectangular sheet and the back wall of the bag at a back wall connecting seal. Each end of the reclosable fastener is sealed to the inside surface of the rectangular sheet of film inwardly of the longitudinal folds of the bag body thereby preventing air or liquids from entering or leaving the bag through the ends of the reclosable fastener. A frangible access substantially parallel to the reclosable fastener being located on the front wall and on the back wall of the bag body adjacent the reclosable fastener and above the back wall connecting seal is provided for exposing the reclosable fastener. The method also includes providing a top seal above the frangible access.
Yet another object of the invention is to provide a method of making a reclosable bag that includes splotching and substantially flattening the ends of the reclosable fastener prior to the step of connecting the front wall connecting flange to the inside surface of the rectangular sheet. In a variant of the invention it is also appreciated that the ends can be flattened by compression molding the ends into the desired shape with or without the use of heat or ultrasonic sealing. Further the flattened ends and/or the bag body can have marks or other machine readable indicia thereon to permit an electric eye or the like to read the marks or indicia and achieve proper registration and alignment of the reclosable fastener with the bag body.
It is yet another object of the present invention to allow the customer/user of the package to open the package from the top, as he or she is accustomed.
It is another object of this invention to overcome the shortcomings of the art by using flanged reclosable fasteners in the bag forming process, and requiring that the operations for making the bag involve sealing two flat, substantially parallel thin surfaces. There is no irregular surface that is sealed to attach the fastener to the front panel, or to carry the fastener through the bagger and down the form, fill and seal tube, or to seal the back-seamed side of the package.
It is an additional object of the invention to have the flanges of the reclosable fastener sized and dimensioned to prevent the flanges from being sealed to the wrong bag wall as described below.
It is a further object of the invention to provide an automatic contamination-free package by sealing the fastener completely inside the package, and providing a hermetically sealed space within the bag body with an airtight and watertight reclosable fastener seal and other bag body seals. In this variant, the package is opened at the perforations of the package to allow the customer/user to get to the gripping flange of the fastener.
It is another object of the present invention to solve these and other problems in the art, and to serve a market that demands hundreds of millions of reclosable plastic bags annually. The objects and features of the present invention, other than those specifically set forth above, will become apparent in the detailed description of the invention set forth below and in the drawings.